But weed smoking appears to be the least of their worries. Illegal parking, camping, drug sales, open alcohol containers and underage drinking were among the “code violations” that Suhr, Breed and Parks and Rec chief Phil Ginsburg said they would be enforcing with vigor. They also warned that anyone illegally parked would be ticketed or towed, and urged celebrators to take any trash with them that they bring in. But marijuana didn’t even pass the lips of a city official until Juvenile Probation Chief Alan Nance got up to speak.

“Underage drinking, drug sales and the use of marijuana by young people is something we have concerns about,” said Nance, who plans to station a number of juvenile probation officers alongside police and park patrol officers in the park on Sunday.

Breed, who last year threatened to shut down the impromptu celebration, said her main goal is to make sure everyone stays safe and respectful — “not to be a buzz kill or judge anybody’s recreational activity.”

“People have a right to assemble in parks, they have a right to enjoy the city so (a ban threat) was probably a little harsh,” she said. “I don’t feel we can say don’t come here for 420, but we can say, ‘Come to San Francisco, but we’re prepared, if you break the law we will enforce it.’ ”

Whether that enforcement will include cracking down on spliff lovers is up to police, she said. Smoking anything, Breed noted, is illegal in city parks, “and I am not by any means condoning any illegal activity including smoking marijuana for non-medical purposes.”

But Suhr said smokers aren’t a big concern of police.

“Sales of marijuana is a felony in this city. I don’t think we are naive enough to think we can stop everyone in San Francisco from smoking medical marijuana or otherwise in San Francisco this weekend,” he said. “If everyone would just be cool, it’s cool. But as soon as it affects everyone else, then it could be the end of something that we are saying already has reached a tipping point.”

The expected celebration will coincide with Easter Sunday and a number of other, sanctioned events in Golden Gate Park. Ginsburg said if residents don’t have a specific reason to be at the park, they might want to stay home.

In case you are wondering, here’s the full list of code violations city officials said they would be cracking down on this Sunday: